播放暫停AVAudioRecorder文件

Question

在我的節目，我希望用戶能夠：

• 記錄了他的聲音，
• 暫停錄音過程中，
• 聽他記錄
• 和然後繼續錄製。

我已經設法達到了可以用AVAudioRecorder和AVAudioPlayer記錄和播放錄音的程度。但每當我嘗試錄製時，暫停錄製然後播放，播放部分就會失敗並且沒有錯誤。

我可以猜測，它沒有播放的原因是因爲音頻文件尚未保存，仍然在內存或其他東西。

有沒有一種方法可以播放暫停的錄音？ 如果有，請告訴我如何

我使用的Xcode 4.3.2

Answer 1

RecordAudioViewController.h

#import <UIKit/UIKit.h> 
#import <AVFoundation/AVFoundation.h> 
#import <CoreAudio/CoreAudioTypes.h> 

    @interface record_audio_testViewController : UIViewController <AVAudioRecorderDelegate> { 

IBOutlet UIButton * btnStart; 
IBOutlet UIButton * btnPlay; 
IBOutlet UIActivityIndicatorView * actSpinner; 
BOOL toggle; 

//Variables setup for access in the class: 
NSURL * recordedTmpFile; 
AVAudioRecorder * recorder; 
NSError * error; 

} 

@property (nonatomic,retain)IBOutlet UIActivityIndicatorView * actSpinner; 
@property (nonatomic,retain)IBOutlet UIButton * btnStart; 
@property (nonatomic,retain)IBOutlet UIButton * btnPlay; 

- (IBAction) start_button_pressed; 
- (IBAction) play_button_pressed; 
@end 

RecordAudioViewController.m

@synthesize actSpinner, btnStart, btnPlay; 
    - (void)viewDidLoad { 
    [super viewDidLoad]; 

//Start the toggle in true mode. 
toggle = YES; 
btnPlay.hidden = YES; 

//Instanciate an instance of the AVAudioSession object. 
AVAudioSession * audioSession = [AVAudioSession sharedInstance]; 
//Setup the audioSession for playback and record. 
//We could just use record and then switch it to playback leter, but 
//since we are going to do both lets set it up once. 
[audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error: &error]; 
//Activate the session 
[audioSession setActive:YES error: &error]; 

    } 


- (IBAction) start_button_pressed{ 

if(toggle) 
{ 
    toggle = NO; 
    [actSpinner startAnimating]; 
    [btnStart setTitle:@"Stop Recording" forState: UIControlStateNormal ]; 
    btnPlay.enabled = toggle; 
    btnPlay.hidden = !toggle; 

    //Begin the recording session. 
    //Error handling removed. Please add to your own code. 

    //Setup the dictionary object with all the recording settings that this 
    //Recording sessoin will use 
    //Its not clear to me which of these are required and which are the bare minimum. 
    //This is a good resource: http://www.totodotnet.net/tag/avaudiorecorder/ 
    NSMutableDictionary* recordSetting = [[NSMutableDictionary alloc] init]; 
    [recordSetting setValue :[NSNumber numberWithInt:kAudioFormatAppleIMA4] forKey:AVFormatIDKey]; 
    [recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey]; 
    [recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey]; 

    //Now that we have our settings we are going to instanciate an instance of our recorder instance. 
    //Generate a temp file for use by the recording. 
    //This sample was one I found online and seems to be a good choice for making a tmp file that 
    //will not overwrite an existing one. 
    //I know this is a mess of collapsed things into 1 call. I can break it out if need be. 
    recordedTmpFile = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent: [NSString stringWithFormat: @"%.0f.%@", [NSDate timeIntervalSinceReferenceDate] * 1000.0, @"caf"]]]; 
    NSLog(@"Using File called: %@",recordedTmpFile); 
    //Setup the recorder to use this file and record to it. 
    recorder = [[ AVAudioRecorder alloc] initWithURL:recordedTmpFile settings:recordSetting error:&error]; 
    //Use the recorder to start the recording. 
    //Im not sure why we set the delegate to self yet. 
    //Found this in antother example, but Im fuzzy on this still. 
    [recorder setDelegate:self]; 
    //We call this to start the recording process and initialize 
    //the subsstems so that when we actually say "record" it starts right away. 
    [recorder prepareToRecord]; 
    //Start the actual Recording 
    [recorder record]; 
    //There is an optional method for doing the recording for a limited time see 
    //[recorder recordForDuration:(NSTimeInterval) 10] 

} 
else 
{ 
    toggle = YES; 
    [actSpinner stopAnimating]; 
    [btnStart setTitle:@"Start Recording" forState:UIControlStateNormal ]; 
    btnPlay.enabled = toggle; 
    btnPlay.hidden = !toggle; 

    NSLog(@"Using File called: %@",recordedTmpFile); 
    //Stop the recorder. 
    [recorder stop]; 
} 
    } 

    - (void)didReceiveMemoryWarning { 
// Releases the view if it doesn't have a superview. 
[super didReceiveMemoryWarning]; 

// Release any cached data, images, etc that aren't in use. 
    } 

    -(IBAction) play_button_pressed{ 

//The play button was pressed... 
//Setup the AVAudioPlayer to play the file that we just recorded. 
AVAudioPlayer * avPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:recordedTmpFile error:&error]; 
[avPlayer prepareToPlay]; 
[avPlayer play]; 

    } 

    - (void)viewDidUnload { 
// Release any retained subviews of the main view. 
// e.g. self.myOutlet = nil; 
//Clean up the temp file. 
NSFileManager * fm = [NSFileManager defaultManager]; 
[fm removeItemAtPath:[recordedTmpFile path] error:&error]; 
//Call the dealloc on the remaining objects. 
[recorder dealloc]; 
recorder = nil; 
recordedTmpFile = nil; 
    } 


    - (void)dealloc { 
[super dealloc]; 
    } 

@end 

RecordAudioViewController.xib

需要2個按鈕。 1用於開始錄製，另一個用於播放錄製

Answer 2

如果要播放錄製內容，那麼必須先停止錄製，然後才能將文件加載到AVAudioPlayer實例中。

如果您希望能夠播放某些錄音，那麼在聽錄音之後再添加更多內容，或在中間說出錄音......然後您就會遇到一些麻煩。

您必須創建一個新的音頻文件，然後將它們組合在一起。

這是我的解決方案：

// Generate a composition of the two audio assets that will be combined into 
// a single track 
AVMutableComposition* composition = [AVMutableComposition composition]; 
AVMutableCompositionTrack* audioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio 
                   preferredTrackID:kCMPersistentTrackID_Invalid]; 

// grab the two audio assets as AVURLAssets according to the file paths 
AVURLAsset* masterAsset = [[AVURLAsset alloc] initWithURL:[NSURL fileURLWithPath:self.masterFile] options:nil]; 
AVURLAsset* activeAsset = [[AVURLAsset alloc] initWithURL:[NSURL fileURLWithPath:self.newRecording] options:nil]; 

NSError* error = nil; 

// grab the portion of interest from the master asset 
[audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, masterAsset.duration) 
        ofTrack:[[masterAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] 
        atTime:kCMTimeZero 
         error:&error]; 
if (error) 
{ 
    // report the error 
    return; 
} 

// append the entirety of the active recording 
[audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, activeAsset.duration) 
        ofTrack:[[activeAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] 
        atTime:masterAsset.duration 
         error:&error]; 

if (error) 
{ 
    // report the error 
    return; 
} 

// now export the two files 
// create the export session 
// no need for a retain here, the session will be retained by the 
// completion handler since it is referenced there 

AVAssetExportSession* exportSession = [AVAssetExportSession 
             exportSessionWithAsset:composition 
             presetName:AVAssetExportPresetAppleM4A]; 
if (nil == exportSession) 
{ 
    // report the error 
    return; 
} 


NSString* combined = @"combined file path";// create a new file for the combined file 

// configure export session output with all our parameters 
exportSession.outputURL = [NSURL fileURLWithPath:combined]; // output path 
exportSession.outputFileType = AVFileTypeAppleM4A; // output file type 

[exportSession exportAsynchronouslyWithCompletionHandler:^{ 

    // export status changed, check to see if it's done, errored, waiting, etc 
    switch (exportSession.status) 
    { 
     case AVAssetExportSessionStatusFailed: 
      break; 
     case AVAssetExportSessionStatusCompleted: 
      break; 
     case AVAssetExportSessionStatusWaiting: 
      break; 
     default: 
      break; 
    } 
    NSError* error = nil; 

    // your code for dealing with the now combined file 
}]; 

我不能充分信貸這項工作，但它是從其他幾個輸入拼湊：

AVAudioRecorder/AVAudioPlayer - append recording to file

（目前我找不到其他鏈接）